I don't see too much discussion about watercooled PCs on TR and even less specifically about watercooled GPUs. I've just recently got my HD 7970 under water and I've been pleasantly surprised with the results so far. The HD 7970 seems to be quite sensitive to higher temps - perhaps more than previous generations. With the custom air cooler I had, I would never see temps going higher than 80 deg C under heavy load when overclocking, yet I had difficulty getting that card stable at much over 1200 Mhz. Raising the voltage over 1.2V at these clocks would cause artifacts, etc, in demanding 3D benchmarks (Heaven).

Now that it's watercooled, I've yet to see it go over 37 deg C at load and seems to be very stable at 1300 Mhz core at 1.225V. I haven't tried pushing it higher. I wasn't expecting such a dramatic reduction in core temp and increase in overclocking headroom. Also, it may be me, but the card just seems to run a bit more smoothly overall now that the core temp has been dropped.

Are any of you other Gerbils watercooling HD 7900 series or GTX 600 series cards? Previous generations? If so, what sort of results have you had?

I used to, back in the day. Danger Den makes some great GPU coolers, but they're kinda pricey.

The results were decent. I didn't compare air to water, but I was able to get decent enough overclocks to be happy. And the first GPU I did this with was the GeForce 5800, a.k.a. the infamous DustBuster (yes I had one).

That said, I'm not sure it's worth the price. You can just save that money up and buy a bigger better GPU a year later instead. GPU fans are relatively quiet these days, so they're not as bad as they used to be unless you're going to insane levels of performance.

If you're trying to make the fastest GPU ever built, though, you'll benefit from water cooling. I have to question just how sane that is, however, given the rapid advancement in computing technology.

No. Custom water cooling definitely isn't a value proposition. Just yet another excuse to spend a bit of extra money on a hobby you find interesting I don't know if I'll be doing it again for future systems, but if was something I've always wanted to try. Finally I had the opportunity.

Danger Den makes a cooler for the HD 7970, but man is it ugly. I mean just look at that thing!

I went with a GPU block from WaterCool, a German company, basically because I liked the look and it go pretty good reviews (though there were only a couple of sites that actually reviewed it - and I think all were German ones). I'm pretty happy with it so far...

My 5970 is watercooled - I went from the stock clocks (which I don't really recall...but they were relatively slow by any measure of the word) to well past 5870 clocks. The VRMs still get a bit toasty even under water, but I've tweaked it so they stay under 100 C at all times. 1 GHz core, 1.2 GHz memory.

Waco wrote:My 5970 is watercooled - I went from the stock clocks (which I don't really recall...but they were relatively slow by any measure of the word) to well past 5870 clocks. The VRMs still get a bit toasty even under water, but I've tweaked it so they stay under 100 C at all times. 1 GHz core, 1.2 GHz memory.

Sorry if this is a dumb question, but how do you measure VRM temps for your 5970? I'd like to be able to check mine...

What water blocks are you guys using? I'm thinking of buying a new card (or two) since I discovered my 6950 isn't quite up to the task of driving my new 3x monitor array. If it happens, I'll probably add the GPU(s) to the loop. I am considering universal blocks though, I don't really care for the notion of having to buy an entirely new block for each GPU upgrade...

Even if it doesn't happen, it's probably time to change tubing; it's turned an odd shade of green even though the water is still clear . Any idea if DangerDen DreamFlex is as good as they claim?

mortifiedPenguin wrote:What water blocks are you guys using? I'm thinking of buying a new card (or two) since I discovered my 6950 isn't quite up to the task of driving my new 3x monitor array. If it happens, I'll probably add the GPU(s) to the loop. I am considering universal blocks though, I don't really care for the notion of having to buy an entirely new block for each GPU upgrade...

Even if it doesn't happen, it's probably time to change tubing; it's turned an odd shade of green even though the water is still clear . Any idea if DangerDen DreamFlex is as good as they claim?

I'm using the WaterCool Heat Killer 79x0 GPU-X3. It had the second best flow-rate and top heat dissipation performance (though not by much) in this shootout covering 6 HD 7970 coolers (the Dangerden is the only HD 7970 cooler I know of that was not tested here). The build quality on the WaterCool stuff is top notch (also have a CPU VRM block by them) and I liked the look of it. They also make coolers for Nvidia cards of course. These are full cover coolers - which as you point out, means you'll likely have to get a new one when you upgrade your GPU. While this aspect is undesirable, the full block coolers really do a much better job cooling the VRMs on the HD7970 (and memory as well). The block seems pretty efficient on my setup. My ambient temp is 22 to 23 deg C and the HD 7970 core and VRMs read about 26-27 deg C at idle; no higher than 37 deg at full load, overclocked.

I'm using the XSPC 7/16 internal diameter tubing. Been pretty good. Nice and flexible and resistant to kinks. I also find it a nice compromise in size between the more popular diameters. I have a bit of clear tubing in my loop, but it's still fairly new, so no word on how it discolors over time.

Last edited by cynan on Wed Jun 13, 2012 12:20 pm, edited 1 time in total.

Madman wrote:I always follow what's going on, but I have never tried the water cooled setups.

What I'm looking for is total silence, and if water cooled setups would allow for that, I would probably try. Zalman reserator some 5+ years ago seemed pretty neat.

But the PSUs are always air cooled, and this sort of breaks the whole fun.

Also, I'm afraid of leaks. I tend to leave my PC unattended from time to time, and some pipe getting loose over hot wires seems to be pretty dangerous.

How silent your watercooled system is basically comes down to the radiator fans and the pump. If you are not concerned with getting maximum cooling performance, you can get some quiet fans and run them at fairly low RPMs. The noise of the pump has a lot to do with placement and care of installation (ie, if you insulate it from the case with vibration absorptive materials, etc). You can also get pumps that are PWM controlled, so you have some flexibility between noise/performance. Theoretically, if your motherboard comes with good fan control software, or if you invest in fan controllers, you could set up a profile so the pump and fans only spin up with temperature. The other thing the noise level depends on is the amount of radiator surface area. Obviously, if you have more rads, you don't need to push as much air over each to achieve the same amount of heat dissipation. All that said, if your objective is to push a bunch of overclocked components to the limit, a water cooled system usually won't be all that quiet - but at least it can be setup to be while you're not pushing your hardware using dynamic fan/pump control.

As far as leaks go, I'm still a little nervous about that too - this being my first time watercooling. So far, so good (only been a few months). If you don't already, I would recommend using compression fittings between the tubing and components. You pay a bit more for them vs barbs perhaps, but they give you a bit more piece of mind re leaks, look better, and generally make assembly/disassembly easier. I'm also using a few rotating angled fittings (all Koolance). I was nervous about those leaking at the rotating joint, but again, so far so good. I kind of needed them in my loop as I have very little space between some of my components - I have a 2x120 rad at the back, a 3x120 rad at the front and my reservoir, cpu, VRM, GPU blocks in between, all inside an Antec 1200, including the rads.

You can get PSUs with fan profiles that are completely silent when they're not being pushed. For example the Seasonic X-series, you can set the fan to shut off with lightest use and spins down drastically with moderate load. The XFX PSUs based on this platform do similar.

cynan wrote:... the full block coolers really do a much better job cooling the VRMs on the HD7970 (and memory as well).

I figured as much. My search for a universal VRM block for GPUs didn't turn up anything. Probably because GPU VRM cooling seems to rely more on thermal adhesives rather than mounting holes. Like Waco says, I'm not all that convinced that the tiny little copper heatsinks we can buy will do a huge amount either.

cynan wrote:I'm using the XSPC 7/16 internal diameter tubing. Been pretty good. Nice and flexible and resistant to kinks. I also find it a nice compromise in size between the more popular diameters. I have a bit of clear tubing in my loop, but it's still fairly new, so no word on how it discolors over time.

Ironically, I'm using XSPC 1/2" ID tubing.

I found that the kink resist is decent but starts to flatten a bit if the bend radius is about 4 inches. I've had my setup since last November, and it started discoloring maybe 2 months in? As an overall brand, I'm pretty satisfied with XSPC's stuff... the rad, pump, block, and res are all from XSPC since I bought a kit but I don't think I'll be trying their tubing again. When I redo the loop I think I'll try out either DreamFlex or just use Tygon.

So, to further the discussion:Think my RX240 can dissipate two 7970s and a 2600k @ 4.8? For that matter... I wonder if my kit pump can handle it.

Is there no dielectric liquid that could be used to transfer heat instead of H2O?

nVidia video drivers FAIL, click for more infoDisclaimer: All answers and suggestions are provided by an enthusiastic amateur and are therefore without warranty either explicit or implicit. Basically you use my suggestions at your own risk.

Surprisingly, it's quite secure using zip ties. Not sure if he's still doing it, but I think there's some one (on the overclock.net forums) who custom builds an "adapter"/(jig?) that allows you to fit the Kuhler to either an nVidia card or an AMD card.

My temps range from 32 C (idle) to about 57-60 C (Furmark for about an hour). I sawed off the fan part that cools the VRM and re-used that. It's a shame I couldn't mod the original heatsink and re-use that though (damn super glue )

mortifiedPenguin wrote: As an overall brand, I'm pretty satisfied with XSPC's stuff... the rad, pump, block, and res are all from XSPC since I bought a kit but I don't think I'll be trying their tubing again. When I redo the loop I think I'll try out either DreamFlex or just use Tygon.

I started with an XSPC Raystorm kit. Came with their new slimmer EK240 rad. The pump in the kit I got was a Laing DDC 3.25. The kit also came with the 7/16 tubing, which is why I'm still using it, but been satisfied so far. Afterwards, I added another EK360 rad (because I wanted to maximize the vertical space I had in the front of the case and leave enough rad capacity in case I wanted to add a second GPU) and the CPU VRM and GPU blocks. The VRM block is pretty low restriction as the VRMs on my board are in a single parallel config (no path around corners and such).

mortifiedPenguin wrote:So, to further the discussion:Think my RX240 can dissipate two 7970s and a 2600k @ 4.8? For that matter... I wonder if my kit pump can handle it.

One 7970 and a 2600k would probably be fine, if you are not trying to overclock much beyond what you could do on air. 2x 7970s plus the CPU I think is a pushing it a bit - even with the RX. As far as the pump, if it's based off of one of the current Laing models (ie, DDC 3.25 or D5), it will be fine. With my DDC 3.25, I'm going through 2 rads, cpu, VRM, GPU block and I still have more than enough flow rate and I wouldn't hesitate adding a second GPU. It is actually better for the DDC 3.X pumps to have a certain amount of flow resistance, particularly if they have a custom top or are installed in an XSPC dual bay reservoir (similar to a custom top) as these pumps can run quite hot at high flow rates, especially when "overclocked" with these custom tops. I've noticed this myself and, ironically, you may end up prolonging the life of such a pump with a bit more resistance in your loop. And as long as flow rate is over a gallon/min, you generally don't really see much difference in performance going higher. If it's one of those cheaper pumps that XSPC used to bundle with the single-bay reservoir kits, then I don't know...

Is there no dielectric liquid that could be used to transfer heat instead of H2O?

You talking about a system failure (leaking)? Because your electronics might survive, but that would still make it terrible to clean up, and if it were to get on any pins, it could prevent stuff from working, even if it didn't fry something.

But thinking along these lines...has anyone made a consumer case that keeps all the water below the electronics? Like a flat case with the motherboard mounted upside-down?

"A life is like a garden. Perfect moments can be had, but not preserved, except in memory. LLAP"

Is there no dielectric liquid that could be used to transfer heat instead of H2O?

3M Fluorinert FC-84 or FC-72, but it cost several hundred dollars per liter.

--SS

Checking the 3M documentation, the thermal conductivity of FC-84 doesn't seem to be any better than for distilled water (both seem to be around 0.06 W/m(deg C)). Furthermore, viscosity of these fluids seem a bit lower than water - which might result in overheating or causing poorer flow rates from the pump - but perhaps the difference is not that significant. The viscosity of FC-72 is quite a bit lower, however.

Obviously the big advantage of these fluids is that they don't conduct electricity so if it leaked, it would just harmlessly evaporate. But as far as cooling performance using standard watercooling components, you're better off with distilled water based coolants, ya know, particularly since, as you pointed out, they cost $$$.

Submersing an entire motherboard in a tank oone fo these fluids might be an interesting idea, but that sounds like a very expensive hobby to me..

Water is best for a reason - it's heat capacity. There aren't any good alternatives.

As for dual 7970s and an overclocked i7 on a single RX240...that's pushing it a bit far. A single RX360 cooled my dual 4870X2s and an overclocked Phenom II X4, but not well. At high loads my water temperatures were a good 20-25 C over room temperature. I would imagine even a single 7970 and i7 would be pushing it unless you don't mind high water temps (in which case...why are you watercooling?).

I run dual 360mm radiators now (with 12 Yate Loon low speed fans) to keep my temperatures WAY down. Even at full load I don't see a 5 C delta over ambient.

Waco wrote:Water is best for a reason - it's heat capacity. There aren't any good alternatives.

As for dual 7970s and an overclocked i7 on a single RX240...that's pushing it a bit far. A single RX360 cooled my dual 4870X2s and an overclocked Phenom II X4, but not well. At high loads my water temperatures were a good 20-25 C over room temperature. I would imagine even a single 7970 and i7 would be pushing it unless you don't mind high water temps (in which case...why are you watercooling?).

I run dual 360mm radiators now (with 12 Yate Loon low speed fans) to keep my temperatures WAY down. Even at full load I don't see a 5 C delta over ambient.

Yup. The heat capacity of water is about 4 times that of these dielectric fluids.

Are you talking 5 deg C delta in water temp? Surely not in CPU core temp

cynan wrote:One 7970 and a 2600k would probably be fine, if you are not trying to overclock much beyond what you could do on air. 2x 7970s plus the CPU I think is a pushing it a bit - even with the RX.

I thought as much. I think I might want to start planning for a second rad then (pretty sure I have a D5 in my dual bay res). I think I can fit an RX120 or similar where the rear outtake fan is... assuming my Gentle Typhoons aren't in the way. Maybe add a second res for more water. Though going by Waco's comments, that probably won't be enough for a second 7970.

Waco wrote:I run dual 360mm radiators now (with 12 Yate Loon low speed fans) to keep my temperatures WAY down. Even at full load I don't see a 5 C delta over ambient.

That's... impressive. I don't suppose both those rads are internally mounted (I don't see your case in your sig).

IIRC, you can actually submerge the whole PC in distilled water and it will work just fine, the problem is usually the dirt and other contaminants. As soon as something like that get inside, you get a firework

I seem to remember one of the boutique manufacturers submerging a full system (minus HDD) in mineral oil a few years back with decent results for zero noise. Supposedly they just left it running in their lobby for a few years before decommissioning it.